In document processing systems, it is well known that customer satisfaction can be improved and maintenance costs reduced if problems with copiers and printers can be detected and resolved before they become serious enough to warrant a service call from the customer. Systems exist that enable printers and copiers to call for service automatically, when sensors detect certain operating parameters outside of permissible ranges. Generally, these systems take effect after a threshold has been reached where the degradation in image quality is likely observable by the user. Given the large number of operating parameters that need to be tracked during operation, a specific defect at a certain level may or may not be a significant problem. The overall effect of a specific defect depends on the cumulative values of the other parameters in the system. Systems do exist that attempt to diagnose failures in document processing systems based on image quality analysis of the print.
An example of such a system is in U.S. Pat. No. 6,665,425 to Sampath et al., issued Dec. 16, 2003. Other examples of test pattern and measurement technology include:
U.S. Pat. No. 6,529,616, for a “TECHNIQUE FOR ACCURATE COLOR-COLOR REGISTRATION MEASUREMENTS,” by Rasmussen, et al., issued Mar. 4, 2003, discloses a test pattern and measurement technique used to allow highly accurate measurements of color-color registration in an image output device that prints in cyan, magenta, yellow, and black. The technique automatically factors out errors originating from skew between the detector and the subject of measurement.
U.S. Pat. No. 6,522,430 directed to “QUANTIFICATION OF MOTION QUALITY EFFECT ON IMAGE QUALITY,” by Dalal et al., issued Feb. 18, 2003, teaches a special test pattern and measurement technique used to allow highly accurate measurements of motion quality defects in an image output device that prints in monochrome or color;
U.S. Pat. No. 6,275,600, to Banker et al., for “MEASURING IMAGE CHARACTERISTICS OF OUTPUT FROM A DIGITAL PRINTER,” issued Aug. 14, 2001, teaches a method for measuring image characteristics of printed output from a digital printer by sending test pattern data to the digital printer, generating a printed image of the test pattern data at the digital printer, scanning the printed image to obtain digital pattern data, and analyzing the digital pattern data of the printed image. The test pattern that is printed includes target objects designed to reveal specific printed image characteristics, and the analysis of the data from scanning the printed image includes the generation of one or more quantitative ratings with respect to printed image characteristics.
Image quality problems occurring in a document processing system are often identified by applying image processing and pattern recognition techniques to analyze specific test patterns. The results are analyzed in conjunction with known generic or unit specific machine data in a diagnostic expert system to assist in the determination of the cause of the problem. Further systems are provided to determine and execute a recommended service procedure such as, for instance, a user guided repair, scheduled maintenance service, parts replacement, and the like. Banding or similar image defect analysis can be accomplished using a series of computer modules and algorithms to analyze specific test patterns via techniques such as image processing and pattern recognition.
In order to accurately diagnose the machine, it may be necessary to print and analyze several different test targets on what have conventionally been several test patterns. As used herein, the term test target is generally used to represent a region of a larger test pattern, although it is possible to have a single test target encompass an entire page. Such test targets typically exist as static pre-defined test patterns (or pages) for a given machine or series of machines. Moreover, the test patterns employed for printing or output devices are generally stored in memory or are uploadable to the output device. After analysis of the output of a test pattern, several failure modes may remain as possible causes and different analyses may become necessary to further narrow down the failure mode. Hence, the printing and analysis process is often repeated several times until the failure mode is accurately determined. To completely diagnose a problem, it may be necessary to print multiple pages of pre-defined test patterns, although only small parts, or targets, of each test pattern are actually needed.
The present invention is directed to an improved system and method wherein the need to print entire test patterns, over several print-analysis iterations, is simplified and expedited. The present invention employs a dynamic test pattern composition process and system, wherein the test targets required for analysis are selected and printed on a test pattern rather than simply printing several patterns having desired test targets. The dynamic selection and printing of test targets enables better utilization of the test pattern and is more efficient in that it potentially reduces the number of printing-analysis cycles. At a minimum, the present invention reduces the time and effort to print the test patterns and to scan the printed samples into electronic form so that they can be further analyzed.
At any time, given the results from user-input and/or prior tests, the diagnostic system of an output device can calculate which sequence of test targets is most likely to be the Optimal Test Target Sequence (OTTS) for the continued diagnostics. Generation of the next test pattern is a constrained optimization problem wherein the optimization criteria is often to maximize the discriminating power between the failure modes of sets of targets or the information obtained from the set of test targets. Ideally, a single or limited number of test patterns can then be generated which contains test targets according to the determined optimal sequence. This is contrasted with conventional systems where, if the test patterns were pre-defined, one would have to choose among the existing test patterns at hand. In order to print the first few test targets from the OTTS, the system may have to print multiple pages of test patterns.
What is needed in this art is method to automatically compose test patterns that are optimized according to the Optimal Test Target Sequence (OTTS) at any given point during the diagnostic sequence to ensure that statistically the minimal number of pages will be printed in order to complete the automatic diagnosis.
In accordance with an aspect of the present invention, there is provided a method for dynamic test pattern generation, including the steps of: automatically selecting a set of test targets as a function of the probability of possible defects and machine performance data and to maximize an optimization criteria; and placing the set of test targets on a digital test pattern.
In accordance with another aspect of the present invention, there is provided a method for automated image quality based diagnostics and remediation of a document processing system, including the steps of: selecting, as a function of potential defects, at least one of a plurality of test targets for output as a test pattern by the document processing system; generating a printed output of the test pattern; obtaining data pertaining to the document processing system, including scanning the printed output to obtain image data pertaining to the output of the at least one selected test target; and analyzing the data to obtain an initial diagnosis, the diagnosis including at least one potential defect as identified in data corresponding to the at least one selected test target, and including performing an image quality analysis of the data corresponding to the data for the at least one selected test target.
In accordance with yet another aspect of the present invention, there is provided a system for automated image quality based diagnosis of a document processing system, comprising: a test selection module, including a dynamic test target selection function, so as to select at least one of a plurality of test targets as a function of a diagnostic request to produce a test pattern; a print engine, operatively associated with the document processing system, for rendering the test pattern; an image quality analysis module that identifies and characterizes defects within a test target on the test pattern produced by print engine and generates key features of the defects for further analysis; and a diagnostic engine that analyzes the data generated by the image quality analysis module to obtain a diagnosis, the diagnosis including at least one diagnosis from a list of potential defects in data corresponding to at least one test pattern image, wherein the diagnostic engine refines the initial diagnosis based on the at least one identified defect.
The present invention will be described in connection with a preferred embodiment, however, it will be understood that there is no intent to limit the invention to the embodiment(s) described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.